The present invention relates to a method for correcting a drift of a printing position and a printing apparatus for practicing the same and, more particular to a method for correcting a drift of a printing position and a printing apparatus for practicing the same such as a wire dot printer and an ink jet recording apparatus in which a drift of a printing position is corrected in a forth and back direction printing or a forth passage printing and a back passage printing.
In a conventional printing apparatus for printing a document data in which a print head moves in a forth and back direction, a printing position drift generates slightly between a printing pattern of a forth passage printing and a printing pattern of a back passage printing. This printing position drift generates in order that a rotation of a carriage drive motor for moving a carriage does not correspond completely to a movement position of the print head.
Namely, a position detection of the print head is practices in accordance with a rotation amount of the carriage drive motor for moving the carriage in a forth and back direction, however a history characteristic exists slightly in a mechanical drive system drive force transmission, which is inserted between the carriage drive motor and the carriage (print head).
An amount of this printing position drift is about 0.1 mm degree, however in a case of the printing of longitudinal ruled lines extending over a plurality of lines, this printing position drift amount is not a negligible amount. Accordingly, in a case of the printing for the document data including the longitudinal ruled lines, in the conventional printing apparatus the back passage printing is give up and but the forth passage printing carried out repeatedly. As a result, it requires a large printing time for the document data and an actual printing speed or a throughput is lowered.
The printing position drift of the printing pattern in the forth and back direction printing can correct and print with this correction, if a present position of the print head (carriage) were detected accurately.
A conventional printing apparatus is disclosed, for example in Japanese Patent Laid-Open No. 64586/1987, in which for a right end arrangement of the printing pattern in the forth and back direction printing, an optimum acceleration/deceleration speed control table for controlling the carriage drive motor for driving the carriage is selected according to taking a look at an observation of the printing result.
Another conventional method for correcting a drift of a printing position is disclosed, for example in Japanese Patent Laid-Open No. 109657/1987, in which during a forth and back direction printing in an ink jet recording apparatus, for correcting of a printing position drift, a correction method for delay correcting a print timing against a position detection according to taking a look at an observation of the printing result.
However, in the above stated prior arts, in the former prior art, all of the printing position drifts during the printing on the way can not correct, because an acceleration/deceleration speed characteristic for the carriage drive motor is put in order at both ends of the carriage.
Further, in the latter prior art, the printing position drift generates due to a speed fluctuation of the print head (carriage) in a series of the printing, because the correction for the printing position drift is practices by setting a delay time at a proper value.